18+ Shanai de Ichiban Kiken na Otoko to Kiss no Aji

Saya, who works in public relations at a publisher, was proposed by her boyfriend on Christmas Eve. However, after her boyfriend carelessly told her "You can work part time after you marry me," she got in a fight with him and ended up breaking up. Saya is focused on her career more than ever, but meets a hot young man. He treats her lightheartedly, leaving a horrible impression. But his true identity is...!!

(Source: Manga Reborn)